| Summary: | 碩士 === 國立海洋大學 === 航運技術研究所 === 90 === This study presents visual observation and frictional performance of the wavy channel at symmetric winglet and winglet type vortex generator. Two wavy channels having corrugation angles of 15 and 30 degrees and a plain channel were examined in the study. The observed range is from Re=300 to Re=2100. For plain channel, laminar flow prevails throughout the test range. A detectable flow re-circulation is seen at the leeside of the wavy channel for 15 degree. This phenomenon is seen even in the first corrugation but is not seen for 15 degree. A very special phenomenon of the spilt and turn around of the dye steak located at the leeward of the second corrugation is observed.
Without vortex generator, the pressure drop of the wavy channel increases significantly with the corrugation angle. The significant increase of the pressure drop is directly linked to the presence of flow-recirculation and the strong turbulence mixing caused by the corrugation.
With symmetric winglet type vortex generator, the increases in the mixing phenomeon at tp-2 and tri-2 are dramatically. Among the winglet type vortex generators,tm-4 is show the best than all others. In this experimental study, tri-2 is the best among all and the ratio of pressure drop is increased to about 10%,compared to the corrugation of θ=30°。
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